1. Field of the Invention
The present invention relates to an ink-jet recording process in which energy is applied to an ink to eject the ink from fine orifices, thereby conducting recording, and an ink-jet recorded image. The present invention is suitable for use in the field of commercial printings such as posters and pamphlets.
2. Related Background Art
The advancement of ink-jet recording techniques in recent years has permitted achieving high-definition images like a silver salt photograph by an ink-jet recording method. Both improvement of inks and improvement of printing media contribute to the achievement of such an image. By the way, printing media having an ink-receiving layer on a base material to enhance ink absorbency are often used as printing media used in the formation of such a high-definition image. However, surfaces of such printing media include both surfaces having high gloss and comparatively matt finished surfaces having poor gloss. On the other hand, the gloss of an image formed on a printing medium varies according to the kind of an ink used. For example, an image formed with an ink containing a water-soluble coloring material, specifically, a dye or the like takes over the gloss of the printing medium as it is. On the other hand, an image formed with an ink containing a water-insoluble coloring material, for example, a pigment tends to become an image little in gloss because the pigment is easy to remain on the surface of the printing medium. Further, an ink containing a photo-curing resin forms an image having an extremely smooth surface because a resin film is formed by irradiation of light after recording. The image often shows high gloss. Therefore, a great difference in visual gloss arises between an image-formed portion and an exposed portion of a printing medium existing complementarily to the image-formed portion according to a combination of the printing medium and the ink. This difference is considered to be a cause that a person feels a sense of incompatibility to a high-definition image formed by ink-jet.
In order to solve such a problem, Japanese Patent Application Laid-Open No. 2002-144551 describes an ink-jet recording process comprising ejecting a plurality of pigment inks of different colors to a printing medium having an ink-receiving layer on a base material to record characters and/or images, wherein an overcoating liquid having a film forming ability is ejected in a proportion of from 30 to 100% by weight based on a shot-in ink quantity per unit area to a recorded portion where a shot-in ink quantity per unit area is at least 50% by weight based on the shot-in ink quantity per unit area when a shot-in ink quantity per unit area of each of the plural pigment inks becomes maximum. In other words, the overcoating liquid is applied to the recorded portion by the pigment inks hard to achieve high surface gloss to form a film, whereby the gloss of the recorded portion is improved.
However, this process has failed to sufficiently cope with various combinations of printing media and inks. In addition, since the film is additionally formed on the ink-applied portion, the visible image portion seems to project from the surface of the printing medium. This fact may give a sense of incompatibility to a person who looks at the image in some cases.
Japanese Patent Application Laid-Open No. 2001-277488 discloses an ink-jet recording process comprising using an ink-jet printer having a plurality of heads for respectively ejecting at least two black inks different in density and an ink containing no colorant used only at a blank portion of a printing medium and ejecting the inks to the printing medium from the plural heads to form an image, wherein the black inks and the ink containing no colorant contain fine polymer particles having an average particle diameter of from 10 to 1,000 nm. The Japanese Patent Application Laid-Open No. 2001-277488 describes at [0021] that the fine polymer particles preferably form a film during or after drying. However, this prior art document does not describe anything about an object of the present invention that a difference in gloss between a black image portion and a blank portion is alleviated. The investigation by the present inventors has revealed that the gloss of an image portion formed by the pigment inks is relatively low, while the gloss of a blank portion formed by the ink containing no colorant and containing the fine polymer particles having a film forming ability is high, and so a difference in gloss between the image portion and the blank portion is not alleviated at all even by this technique.